Tunnel magnetoresistive sensor having leads supporting three dimensional current flow

ABSTRACT

An apparatus, according to one embodiment, includes: a transducer structure having: a lower shield, an upper shield above the lower shield, a current-perpendicular-to-plane sensor between the upper and lower shields, an electrical lead layer between the sensor and one of the shields, and a spacer layer between the electrical lead layer and the one of the shields. The upper and lower shields provide magnetic shielding. The electrical lead layer is in electrical communication with the sensor. A conductivity of the electrical lead layer is higher than a conductivity of the spacer layer. A width of the electrical lead layer in a cross-track direction is greater than the width of a free layer of the sensor.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic heads, e.g., magnetictape heads, which include current-perpendicular-to-plane (CPP) sensorshaving hard spacers incorporated therewith.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

SUMMARY

An apparatus, according to one embodiment, includes: a transducerstructure having: a lower shield, an upper shield above the lowershield, a current-perpendicular-to-plane sensor between the upper andlower shields, an electrical lead layer between the sensor and one ofthe shields, and a spacer layer between the electrical lead layer andthe one of the shields. The upper and lower shields provide magneticshielding. The electrical lead layer is in electrical communication withthe sensor. A conductivity of the electrical lead layer is higher than aconductivity of the spacer layer. A width of the electrical lead layerin a cross-track direction is greater than the width of a free layer ofthe sensor.

An apparatus, according to another embodiment, includes: a transducerstructure having: a lower shield, an upper shield above the lowershield, a current-perpendicular-to-plane sensor between the upper andlower shields, a first electrical lead layer between the sensor and theupper shield, a second electrical lead layer between the sensor and thelower shield, a first spacer layer between the first electrical leadlayer and the upper shield, and a second spacer layer between the secondelectrical lead layer and the lower shield. The upper and lower shieldsprovide magnetic shielding. The first and second electrical lead layersare in electrical communication with the sensor. A width of the secondelectrical lead layer in a cross-track direction is greater than a widththe sensor.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8A is a partial cross-sectional view of a transducer structureaccording to one embodiment.

FIG. 8B is a media-facing side perspective view taken from circle 8B inFIG. 8A according to one embodiment.

FIG. 8C is a partial side view of a media-facing side of a transducerstructure according to one embodiment.

FIG. 9 is a partial cross-sectional view of a transducer structureaccording to one embodiment

FIG. 10 is a partial cross-sectional view of a transducer structureaccording to one embodiment

FIG. 11A is a partial perspective view of a media facing side of atransducer structure in the cross track direction according to oneembodiment.

FIG. 11B depicts the current flow into the sensor of FIG. 11A accordingto one embodiment.

FIG. 11C depicts the current flow into a sensor according to oneembodiment.

FIG. 11D depicts the current flow into a sensor according to oneembodiment.

FIGS. 12A-12C show voltage maps at the surface of the sensor accordingto various embodiments.

FIG. 13 is a partial cross-sectional view of a transducer structureaccording to one embodiment.

FIG. 14 is a partial cross-sectional view of a transducer structureaccording to one embodiment.

FIG. 15A is a partial cross-sectional view of a transducer structureaccording to one embodiment.

FIG. 15B is a partial side view of a media-facing side of a transducerstructure according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems having one or more heads which implement CPPsensors having hard spacers incorporated therewith. Thus, variousembodiments described herein may reduce the probability of sensorshorting for CPP sensors, e.g., such as tunneling magnetoresistive (TMR)sensors, giant magnetoresistive (GMR), etc., as will be described infurther detail below.

In one general embodiment, an apparatus includes: a transducer structurehaving: a lower shield, an upper shield above the lower shield, acurrent-perpendicular-to-plane sensor between the upper and lowershields, an electrical lead layer between the sensor and one of theshields, and a spacer layer between the electrical lead layer and theone of the shields. The upper and lower shields provide magneticshielding. The electrical lead layer is in electrical communication withthe sensor. A conductivity of the electrical lead layer is higher than aconductivity of the spacer layer. A width of the electrical lead layerin a cross-track direction is greater than the width of a free layer ofthe sensor.

In another general embodiment, an apparatus includes: a transducerstructure having: a lower shield, an upper shield above the lowershield, a current-perpendicular-to-plane sensor between the upper andlower shields, a first electrical lead layer between the sensor and theupper shield, a second electrical lead layer between the sensor and thelower shield, a first spacer layer between the first electrical leadlayer and the upper shield, and a second spacer layer between the secondelectrical lead layer and the lower shield. The upper and lower shieldsprovide magnetic shielding. The first and second electrical lead layersare in electrical communication with the sensor. A width of the secondelectrical lead layer in a cross-track direction is greater than a widththe sensor.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the drive 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, read-only memory (ROM) device, etc., embedded intoor coupled to the inside or outside of the tape cartridge 150. Thenonvolatile memory is accessible by the tape drive and the tapeoperating software (the driver software), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeable. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked magnetorisistive (MR) headassembly 200 includes two thin-film modules 224 and 226 of generallyidentical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (—),cadmium zinc telluride (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type of CPP sensor, includingthose based on MR, GMR, TMR, etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used linear tape-open (LTO) tape head spacing. The openspace between the modules 302, 304, 306 can still be set toapproximately 0.5 to 0.6 mm, which in some embodiments is ideal forstabilizing tape motion over the second module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

With continued reference to the above described apparatuses, it would beadvantageous for tape recording heads to include TMR sensor technology.Furthermore, with on-going decrease in data track width in magneticstorage technologies, TMR sensors enable readback of data in ultra-thindata tracks due to their high level of sensitivity in such smalloperating environments.

As will be appreciated by one skilled in the art, by way of example, TMRis a magnetoresistive effect that occurs with a magnetic tunneljunction. TMR sensors typically include two ferromagnetic layersseparated by a thin insulating barrier layer. One layer (the referencelayer) has a fixed magnetization while the magnetic moment of the otherlayer is free to rotate. When the barrier layer is thin enough e.g.,less than about 15 angstroms, electrons may tunnel from oneferromagnetic layer to the other ferromagnetic layer, passing throughthe insulating barrier. Variations in the barrier resistance, caused bythe influence of external magnetic fields from a magnetic medium on thefree ferromagnetic layer of the TMR sensor, correspond to data stored onthe magnetic medium.

In tape recording, friction between asperities on the tape and theductile metallic films in the sensor gives rise to deformation forces inthe direction of tape motion. As a result, an electrical short may becreated by the scratching and/or smearing of the ductile layers. Thismay create bridges of conductive material across the sensor.Particularly, the asperities tend to plow through ductile magneticmaterial, e.g., from one or both shields, smearing the metal across theinsulating material, and thereby creating an electrical short thatreduces the effective resistance of the sensor and diminishes thesensitivity of the sensor as a whole. If one or more sensors in amultichannel tape head are rendered non-functional, then tape drivecartridge capacity may be diminished.

Those familiar with TMR sensor technology would expect that a TMR sensormight experience shorting in a contact recording environment such asmagnetic tape data storage due to abrasive asperities embedded in therecording medium scraping across the thin insulating layer during tapetravel, thereby creating the aforementioned shorting. The inventorshave, in fact, observed the tendency of such shorting occurrences.

Typical TMR sensors in hard disk drive applications are configured to bein electrical contact with the top and bottom shields of read headtransducers. In such configurations the current flow is constrained totraveling between the top shield and the bottom shield through thesensor, by an insulator layer with a thickness of about 3 to about 100nanometers (nm) proximate to the sensor stack, and thicker further away.This insulator layer extends below the hard bias magnet layer toinsulate the bottom of the hard bias magnet from the bottom shield/leadlayers, and isolates the edges of the sensor from the hard bias magnetmaterial. In a tape environment, where the sensor is in contact with thetape media, ductile transport of the bottom shield material and/or thehard bias magnet material may bridge the insulation layer separating thehard bias magnet from the bottom lead and lower shield (bottom lead),thereby shorting the sensor. Further, sensor and/or shield deformationor smearing may create a conductive bridge across a tunnel barrier layerin a TMR sensor. Such tunnel barrier layer may be only 12 angstroms wideor less.

In disk drives, conventional TMR sensor designs are acceptable becausethere is minimal contact between the head and the media. However, fortape recording, the head and the media are in constant contact. Headcoating has been cited as a possible solution to these shorting issues;however tape particles and asperities have been known to scratch throughand/or wear away these coating materials as well. Because the tunnelbarrier layer of a conventional TMR sensor is extremely thin, there is apropensity for electrical shorting due, e.g., to scratches, materialdeposits, surface defects, films deformation, etc.

Embodiments described herein implement novel spacer layers incombination with TMR sensors. As a result, some of the embodimentsdescribed herein may be able to reduce the impact of shorting in themost common areas where shorting has been observed, e.g. the areas onopposite sides of the sensor between the shields.

The potential use of TMR sensors in tape heads has heretofore beenthought to be highly questionable, as tape heads include multiplesensors, e.g., 16, 32, 64, etc., on a single die. If one or more ofthose sensors becomes inoperable due to the aforementioned shorting, thehead as a whole may not be able to function properly and would need tobe replaced for proper operation of the apparatus.

Furthermore, tape heads with TMR sensors, a currentperpendicular-to-plane sensor, may short with a single event. Thus, TMRsensors are more susceptible to shorting due to scratches thanconventional current in-plane type sensors which demonstrate diminishedsensor output after at least two shorting events across different partsof the sensor.

TMR sensors comprised of non-conducting, durable films configured tomitigate shorting across the MgO tunnel barrier caused by defects in themoving media may also in turn lower electrical resistance. Inconventional tape heads with TMR sensors as described, current flowsthrough thin leads positioned between the sensor stack andnon-conducting films. In this design, current density through the tunnelvalve barrier may be highest at the end furthest from the media bearingsurface. In other words, the region of the sensor having the highestcurrent is the region least influenced by magnetic flux from the medium,thereby resulting in a loss of head output compared to a head havingcurrent flowing purely orthogonal to the sensor plane.

Various embodiments described herein include a tunnel valve structurethat has non-conducting spacers to buffer the shields from thinelectrical lead layers delivering current to the tunnel valve sensor.The embodiments provide a uniform current flow directed across theheight of the sensor by implementing an insulating spacer between theshield and the adjacent lead, where the insulating spacer has aperimeter proximate to the sensor periphery, thereby urging current toflow from the shield, around the edges of the spacer to the lead, andthrough the sensor.

FIGS. 8A-8C depict an apparatus 800, in accordance with one embodiment.As an option, the present apparatus 800 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. However, suchapparatus 800 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 800 presented herein may be used in any desired environment.Thus FIGS. 8A-8C (and the other FIGS.) may be deemed to include anypossible permutation.

Apparatus 800 includes a magnetic read transducer 802. Although FIGS.8A-8C illustrate only a single magnetic read transducer 802, apparatus800 may include one or more additional magnetic read transducers on aremainder of a module, e.g., in an array such as in FIGS. 2B-4.Accordingly, the components and/or configurations of magnetic readtransducer 802 may be incorporated in any magnetic read transducerdescribed herein.

The magnetic read transducer 802 includes acurrent-perpendicular-to-plane sensor 808, e.g., a tunnelmagnetoresistive (TMR) sensor.

According to some embodiments, the sensor 808 may be configured as adata sensor for reading data tracks of a magnetic medium.

According to other embodiments, the sensor 808 may be configured as aservo pattern reading sensor of a servo reader. For example, the sensor808 may be configured as a servo pattern reading sensor where apparatus800 includes one or more arrays of data readers and/or writers and oneor more servo track readers for reading servo data on a medium.

Looking to FIG. 8A, apparatus 800 includes a transducer structure 802which has a lower shield 804 above a wafer 803 and optional undercoat805. An upper shield 806 is positioned above the lower shield 804 (e.g.,in a deposition direction thereof). A CPP sensor 808 (e.g. such as a TMRsensor, GMR sensor, etc.) is positioned between the upper and lowershields 806, 804 in an intended direction 852 of media travelthereacross. As would be appreciated by one skilled in the art, upperand lower shields 806, 804 preferably provide magnetic shielding for theCPP sensor 808. Thus, one or both of the upper and lower shields 806,804 may desirably include a magnetic material of a type known in theart, such as permalloy or CZT.

Furthermore, as shown in FIG. 8A, the active TMR region of the sensor808 includes a free layer 818, a tunnel barrier layer 820 and areference layer 822 e.g., of conventional construction. According tovarious embodiments, the free layer 818, the tunnel barrier layer 820and/or the reference layer 822 may include construction parameters,e.g., materials, dimensions, properties, etc., according to any of theembodiments described herein, and/or conventional constructionparameters, depending on the desired embodiment. Illustrative materialsfor the tunnel barrier layer 820 include amorphous and/or crystallineforms of, but are not limited to, TiOx, MgO and Al₂O₃.

FIG. 8A further includes a first electrical lead layer 810 positionedbetween the sensor 808 and the upper shield 806 (e.g., the shieldclosest thereto). Moreover, a second electrical lead layer 812 isincluded between the sensor and the lower shield 804 (e.g., the shieldclosest thereto). The first and second electrical lead layers 810, 812are preferably in electrical communication with the sensor 808, e.g., toenable an electrical current to pass through the sensor 808.

First and second spacer layers 814, 816 are also included in thetransducer structure 802. The spacer layers 814, 816 are dielectric insome approaches, but may be conductive in other approaches. The spacerlayers 814, 816 preferably have a very low ductility, e.g., have a highresistance to bending and deformation in general, and ideally a lowerductility than refractory metals such as Ir, Ta, and Ti. First spacerlayer 814 is positioned such that it is sandwiched between the firstelectrical lead layer 810 and the upper shield 806 (e.g., the shieldclosest thereto) at the media facing side 850. Similarly, the secondspacer layer 816 is positioned between the second electrical lead layer812 and the lower shield 804 (e.g., the shield closest thereto) at themedia facing side 850.

In a preferred embodiment, the thin electrical leads 810, 812 extendlaterally beyond one or both of the sides of the sensor in the trackwidth direction. Preferably, the width of one or both of the electricalleads 810, 812 is at least 1½ times the width w₂ of the free layer 818at the media facing side, and may preferably be at least the width ofthe free layer 818 plus 2λ the stripe height of the free layer.

Extending the thin electrical lead layers beyond three sides of thesensor may reduce resistance and urge current to travel through thesensor near the media facing side 850 where the magnetic flux from themedia is strongest, thereby improving signal output. Furthermore, anapparatus where the edges of an insulating spacer layer are proximate tothe edges of the sensor in a cross track direction may provide a sensingstructure that is resistant to deformation and shorting and has lowerlead resistance to the tunnel valve device. In such a structure, theclose proximity of three edges of the spacer to the three edges of thesensor stack may assist current flow into the sensor via all three sidesof the sensor thereby increasing density of current flow towards themedia facing side.

A schematic of the third dimension of the sensor region showing thecross-track direction 854 is illustrated in FIG. 8B as selected fromcircle 8B of FIG. 8A. Looking to FIG. 8B, the second spacer layer 816may be positioned between the lower shield 804 and the second electricallead layer 812 in the direction 852 of media travel with planes ofdeposition of all layers extending in a cross-track direction 854. Asshown in FIG. 8B, the sensor 808 which includes a reference layer 822, atunnel barrier region 820, and a free layer 818 may be positioned on theopposite side of the electrical lead layer 812 from the spacer layer816. In an exemplary embodiment, the width w₁ of the spacer layer 816 ina cross-track direction 854 may be as wide as the width w₂ of the freelayer 818 of the sensor 808. In some approaches, the spacer layer 816present between the lower shield 804 and the electrical lead layer 812may have a width w₁ in the cross-track direction 854 that may be greaterthan the width w₂ of the sensor 808 at the media facing side.

Referring to FIG. 8A, but not shown in FIG. 8B, one embodiment may havethe first spacer 814 positioned on the opposite side of the sensor 808between the upper shield 806 and a first electrical lead layer 810. Thewidth of the first spacer 814 may have a width in the cross-trackdirection 854 that may be greater than the width w₂ of the free layer818 of the sensor 808. Moreover, in other approaches, the spacer layer814 present between the upper shield 806 and the electrical lead layer810 may have a width in the cross-track direction 854 greater than awidth w₂ of the sensor 808 at the media facing side thereof.

As shown in FIG. 8B, the thin electrical lead 812 extends laterallybeyond the sides of the sensor in the track width direction. Preferably,the width of the electrical lead 812 is at least 1½ times the width w₂of the free layer 818 at the media facing side, and may preferably be atleast the width of the free layer 818 plus 2× the stripe height of thefree layer.

FIG. 8C shows a top view of an illustrative embodiment of the transducer802 in which the electrical lead layers 810, 812 may be in electricalcommunication with the upper and lower shields 806, 804. The edges ofthe spacer layers 814, 816 may be proximate to the edges of the sensor808 but separated therefrom by the respective electrical lead layer 810,812. An insulating layer 832 may at least partially surround the hardbias 830 such that the insulating layer 832 may be positioned betweenthe hard bias 830 and the sensor 808 as well as between the hard bias830 and the electrical lead layer 810.

With continued reference to FIGS. 8A and 8C, although it is preferredthat a spacer layer is included on either side of the sensor 808 alongthe intended direction 852 of tape travel, some embodiments may includeonly one spacer layer positioned between one of the leads and the shieldclosest thereto.

As described above, it is not uncommon for tape asperities passing overthe sensor to smear the material of an upper or lower shield onto theopposite shield, thereby potentially shorting the sensor. The closeproximity of the spacer layers, which may be non-conducting films, tothe sensing structure may resist deformation and thus smearing.Moreover, because the first and second electrical lead layers 810, 812are separated from the upper and lower shields 806, 804 at media facingside by the first and second spacer layers 814, 816 respectively, theprobability of a smear bridging the first and second electrical leadlayers 810, 812 at the sensor is reduced.

Thus, as illustrated in FIG. 8A, it is preferred that the first andsecond spacer layers 814, 816 are positioned at the media facing side850 of the transducer structure 802, e.g., such that the sensor 808and/or electrical lead layers 810, 812 are separated from the upper andlower shields 806, 804 thereby reducing the chance of a shorting eventoccurring.

In an illustrative embodiment shown in FIG. 8A, the spacer layer 816 maybe present between the lower shield 804 and the electrical lead layer812, where the spacer layer 816 may extend beyond a back edge 826 of thesensor 808 in an element height H direction. In another embodiment, thespacer layer 814 may be present between the upper shield 806 and theelectrical lead layer 810, wherein the spacer layer 814 may extendbeyond a back edge 826 of the sensor 808 in an element height Hdirection.

Moreover, it is preferred that the material composition of the first andsecond spacer layers 814, 816 is sufficiently resistant to smearingand/or plowing of conductive material across the sensor 808. Thus, thefirst and second spacer layers 814, 816 are preferably hard, e.g., atleast hard enough to prevent asperities in the tape passing over thetransducer structure 802 from causing deformations in the media facingside 850 of the transducer structure 802 which affect the performance ofthe sensor 808. In preferred embodiments, the first and/or second spacerlayers 814, 816 include aluminum oxide. However, according to variousembodiments, the first and/or second spacer layers 814, 816 may includeat least one of aluminum oxide, chrome oxide, silicon nitride, boronnitride, silicon carbide, silicon oxide, titanium oxide, ceramics,titanium nitride, zirconium nitride, etc., and/or combinations thereof.In an exemplary embodiment, the spacer layers 814, 816 may preferablyinclude silicon nitride.

Without wishing to be bound by any theory, it is believed that theimproved performance experienced by implementing aluminum oxide spacerlayers 814, 816 may be due to the low ductility of alumina, relativelyhigh hardness, and low friction resulting between the aluminum oxidespacer layers and defects (e.g., asperities) on a magnetic tape beingpassed thereover. This is particularly apparent when compared to thehigher resistance experienced when metal films and/or coating films areimplemented. Specifically, coatings on the media facing side may not beeffective in preventing shorting because underlying films (e.g., such aspermalloy) are still susceptible to indentation, smearing, plowing,deformation, etc.

Thus, in an exemplary approach, the first and/or second spacer layersmay include an aluminum oxide which may preferably be amorphous.Moreover, an amorphous aluminum oxide spacer layer may be formed usingsputtering, atomic layer deposition, etc., or other processes whichwould be appreciated by one skilled in the art upon reading the presentdescription. According to another exemplary approach, the first and/orsecond spacer layers may include an at least partially polycrystallinealuminum oxide.

Furthermore, in various embodiments, the first and/or second electricallead layers 810, 812 may include any suitable conductive material, e.g.,which may include Ir, Ru, Pt, NiCr, Ta, Cr, etc.; a sandwiched structureof Ta (e.g. Ta/X/Ta); conductive hard alloys such as titanium nitride,boron nitride, silicon carbide, and the like.

Although first and second spacer layers 814, 816 separate first andsecond electrical lead layers 810, 812 from the upper and lower shields806, 804 at the media facing side 850 of the transducer structure 802,the first and/or second electrical lead layers 810, 812 are preferablystill in electrical communication with the shields closest thereto.

However, it should be noted that the embodiment illustrated in FIGS.8A-8C is in no way intended to limit the invention. Although theelectrical lead layers 810, 812 depicted in FIG. 8A are electricallyconnected to upper and lower shields 806, 804 respectively, in otherembodiments, one or both of the electrical lead layers 810, 812 may notbe electrically connected to the respective shields. According to oneexample, the first and second electrical lead layers may be stitchedleads, e.g., see FIG. 15, rather than each of the lead layers 810, 812having a single lead layer as seen in FIG. 8A. Thus, neither of thefirst or second electrical lead layers may be in electricalcommunication with the shields according to some embodiments, as will bedescribed in further detail below.

The electrically conductive layer(s) may have a higher conductivity thanthe spacer layer. Thus, the spacer layer in some embodiments may beelectrically insulating or a poor conductor. In further approaches, theproduct of the spacer layer thickness multiplied by the conductivity ofthe spacer layer may be less than a product of the electrical lead layerthickness multiplied by the conductivity of the electrical lead layerassociated with the spacer layer, e.g., positioned on the same side ofthe sensor therewith.

FIGS. 9-10 depict an apparatus 860, in accordance with one embodiment.As an option, the present apparatus 860 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. However, suchapparatus 860 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 860 presented herein may be used in any desired environment.Thus FIGS. 9-10 (and the other FIGS.) may be deemed to include anypossible permutation.

In FIGS. 9-10, only a single spacer layer is present according to oneembodiment. In one approach shown in FIG. 9, the spacer layer 814 isbetween the sensor 808 and the upper shield 806 and one electrical leadlayer 810 between the spacer layer 814 and the sensor 808 at the mediafacing side 850. An insulating spacer or electrical lead layer is notpresent between the sensor 808 and the lower shield 804. According tothis embodiment, the charge current may travel from the upper shield 806along the electrical lead layer 810 into the sensor 808, and then mayflow out to the lower shield 804, or vice versa.

In another approach, as shown in FIG. 10, a spacer layer 816 is betweenthe sensor 808 and the lower shield 804 and one electrical lead layer812 is between the spacer layer 816 and the sensor 808 at the mediafacing side 850. In this approach, no spacer or electrical lead layer ispresent between the sensor 808 and the upper shield 806. According tothis embodiment, the charge current may travel from the lower shield 804along the electrical lead layer 812 into the sensor 808, and then mayflow out to the upper shield 806, or vice versa.

FIGS. 11A-11D show the current flow through the sensor according to twodifferent embodiments. According to one embodiment, FIG. 11A shows thecurrent 880 (black arrows) flowing in the electrical lead layer 810toward the back and sides of the sensor 808. The insulating spacer 816below the wider electrical lead layer 812 is proximate to the perimeterof the sensor 808. Furthermore, FIG. 11B shows the current 880 (blackarrows) flowing toward the rear of the sensor periphery (represented bydashed lines) where the edges of the insulating spacer 816 may beproximate to the edges of the sensor 808 as shown in FIG. 11A. In apreferred embodiment, the stripe height SH of the sensor is about onehalf the width W of the sensor 808. See FIGS. 11A and 11B. Moreover, awidth W_(L) of each extension of the electrical lead layer 810 beyondthe lateral side of the sensor in the cross-track direction ispreferably at least about ½ W.

Extensions of the electrical lead layer 810 positioned beyond thelateral sides of the sensor in the cross-track direction may beasymmetrical, e.g., having different widths W_(L), on only one side ofthe sensor, etc. FIGS. 11C and 11D illustrate other embodiments in whichthe extensions of the electrical lead layer 810 beyond the lateral sidesof the sensor in the cross-track direction are asymmetrical.

Adding laterally-located lead portions relative to the free layer of thesensor 808 may improve performance of the free layer. In sensor layersnot having laterally-located lead portions, there may be up to about a20% difference in the voltage drop (or loss) across the sensor at themedia facing side 850 compared to the voltage drop across the area nearthe back edge of the sensor farthest from the media facing side 850.However, adding laterally-located lead portions to the sensor layer toincrease current flow may reduce the aforementioned 20% difference inthe voltage drop by a factor of about 1.5 or more.

FIGS. 12A-C show exemplary voltage maps of the surface of a sensor inthree different cases. FIG. 12A shows the voltage map of a surface of asensor with no laterally-located lead portions. FIGS. 12B and 12C aremodeled voltage maps of one half a surface of a sensor with symmetricallaterally-located lead portions and a surface of the sensor withlaterally-located lead portions and the hard bias (see FIG. 8C),respectively. FIG. 12C illustrates that there is a small improvement inthe current flow distribution due to the parallel path for currentprovided by the hard bias, which is in communication with the top lead.The two voltage maps with the laterally-located lead portions, as wellas the portion located at end of the sensor furthest from the mediafacing surface show the voltage lines curving around to reflect thecurrent flowing from the side, and hence an increased uniformity ofcurrent density over the surface area of the sensor.

Although the operating voltage may be increased in some approaches topartially compensate for loss of output due to voltage drop along thelength of the sensor layer, it should be noted that the operatingvoltage is preferably not increased to a value above a threshold value.The threshold value for the operating voltage of a given approach may bepredetermined, calculated in real time, be set in response to a request,etc. According to an exemplary approach, the threshold value for theoperating voltage may be determined using the breakdown voltage(s) ofthe transducer structure layers, e.g., based on their materialcomposition, dimensions, etc.

Looking back to FIG. 8A, in some embodiments, differences in resistivitymay also be used to minimize the voltage drop along the length of thesensor layer 808. In order to ensure that sufficient current passesthrough the sensor layer 808 near the media facing side 850, it ispreferred that the resistance of the sensor layer 808, as for exampledue to tunnel barrier resistivity in a TMR, is high relative to theresistance of the electrical lead layers 810, 812. By creating adifference in the relative resistance of the adjacent layers, voltagedrop may desirably be reduced along the height of the sensor layer 808.

This relative difference in resistance values may be achieved by formingthe sensor layer 808 such that it has a relatively high barrierresistivity, while the electrical lead layers 810, 812 may have a higherthickness, thereby resulting in a lower resistance value. However, itshould be noted that the thickness of the electrical lead layers 810,812 is preferably greater than about 2 nm. The thin film resistivity ofa given material typically increases as the dimensions of the materialdecreases. As will be appreciated by one skilled in the art upon readingthe present description, the resistivity of a material havingsignificantly small dimensions may actually be higher than for the samematerial having larger dimensions, e.g., due to electron surfacescattering. Moreover, as the thickness of the electrical lead layers810, 812 decreases, the resistance thereof increases. Accordingly, thethickness of the first and/or second electrical lead layers 810, 812 ispreferably between about 2 nm and about 20 nm, more preferably betweenabout 5 nm and about 15 nm, but may be higher or lower depending on thedesired embodiment, e.g., depending on the material composition of thefirst and/or second electrical lead layers 810, 812. Moreover, thethicknesses (in the deposition direction) of the first and/or secondspacer layers 814, 816 are preferably between about 5 nm and about 50nm, but may be higher or lower depending on the desired embodiment. Forexample, spacer layers having a relatively hard material composition maybe thinner than spacer layers having a material composition which isless hard. The magnetic spacing between the shields is typicallyadjusted for proper readback at a given operating point. This mayconstrain the allowed thickness range available for leads and spacers.

Looking to FIG. 13, apparatus 900 depicts a transducer structure 902 inaccordance with one embodiment. As an option, the present apparatus 900may be implemented in conjunction with features from any otherembodiment listed herein, such as those described with reference to theother FIGS. Specifically, FIG. 13 illustrates variations of theembodiment of FIG. 8A depicting several exemplary configurations withinthe transducer structure 902. Accordingly, various components of FIG. 13have common numbering with those of FIG. 8A.

However, such apparatus 900 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the apparatus 900 presented herein may be used in any desiredenvironment. Thus FIG. 13 (and the other FIGS.) may be deemed to includeany possible permutation.

Looking to FIG. 13, apparatus 900 includes a transducer structure 902having spacer layers 914, 916 sandwiched between shields 806, 804 andelectrical lead layers 810, 812 respectively at the media facing side850. One embodiment may include a spacer layer 916 between the lowershield 804 and the electrical lead layer 812, where the spacer layer 916may not extend beyond a back edge 826 of the sensor 808 in an elementheight H direction. Moreover, the conductivity of the electrical leadlayer 812 may be higher than the conductivity of the spacer layer 916.

As an option, a spacer layer 914 may be present between the upper shield806 and the electrical lead layer 810, where the spacer layer 914 maynot extend to a back edge 826 of the sensor 808 in an element height Hdirection. Looking to FIG. 8B for reference, in a preferred embodimentof the transducer 902, the width of the spacer layer 916 in across-track direction 854 may be greater than the width w₂ of the freelayer 818 of the sensor 808.

A spacer layer may be formed full film, after which a via may becreated, e.g., using masking and milling, and filling the via with thestud material, e.g., using atomic layer deposition (ALD), after whichthe stud may optionally be planarized. Moreover, as shown in FIG. 13, itshould be noted that insulating layer 824 may be thicker than sensor808, thereby causing first electrical lead layer 810 and first spacerlayer 914 to extend in the intended tape travel direction 852 beforecontinuing beyond the back edge 826 of the sensor 808 farthest from themedia facing side 850, e.g., as a result of manufacturing limitations,as would be appreciated by one skilled in the art upon reading thepresent description.

The spacer layers 914, 916 may provide protection against smearing atthe media facing side 850 while also allowing for the shields 806, 804to be in electrical communication with the electrical lead layers 810,812. It follows that one or both of the shields 806, 804 may serve aselectrical connections for the transducer structure 902. According tothe present embodiment, the shields 806, 804 function as the leads forthe transducer structure 902. Moreover, the current which flows towardsthe media facing side 850 tends to generate a magnetic field which iscanceled out by the magnetic field created by the current which flowsaway from the media facing side 850.

Looking to FIG. 14, apparatus 1000 depicts a transducer structure 1002in accordance with one embodiment. As an option, the present apparatus1000 may be implemented in conjunction with features from any otherembodiment listed herein, such as those described with reference to theother FIGS. Specifically, FIG. 14 illustrates variations of theembodiment of FIG. 8A depicting several exemplary configurations withinthe transducer structure 1002. Accordingly, various components of FIG.14 have common numbering with those of FIG. 8A.

However, such apparatus 1000 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the apparatus 1000 presented herein may be used in any desiredenvironment. Thus FIG. 14 (and the other FIGS.) may be deemed to includeany possible permutation.

The electrical lead layers 810, 812 may or may not be in directelectrical communication with the associated shield. Looking to FIG. 14,in embodiments of the transducer structure 1002 where the spacer layers1014, 1016 are insulative, various mechanisms for providing current tothe sensor may be implemented. First and second electrical lead layers810, 812 are in electrical communication with the upper and lowershields 806, 804 respectively, by implementing studs 1022, 1020 at alocation recessed from the media facing side 850. Furthermore, lookingto FIG. 8B for reference, in a preferred embodiment of the transducer1002, the width of the spacer layer 1016 in a cross-track direction 854may be greater than the width w₂ of the free layer 818 of the sensor808. In some approaches, lateral sides of each lead layer 810, 812flanking the sensor in the cross track direction may be in directelectrical contact with the shield closest thereto. In other approaches,the studs may wrap around the sides of the spacers to provide currentflow between each shield and the associated lead layer.

Studs 1022, 1020 preferably have about the same thickness as first andsecond spacer layers 1014, 1016 respectively. Moreover, studs 1022, 1020are preferably positioned behind or extend past an end of the sensorlayer 808 which is farthest from the media facing side 850.

Referring to FIGS. 15A and 15B, apparatus 1100 depicts a transducerstructure 1102 in accordance with one embodiment. As an option, thepresent apparatus 1100 may be implemented in conjunction with featuresfrom any other embodiment listed herein, such as those described withreference to the other FIGS. Specifically, FIGS. 15A-15B illustratesvariations of the embodiment of FIG. 8A depicting several exemplaryconfigurations within the transducer structure 1102. Accordingly,various components of FIGS. 15A-15B have common numbering with those ofFIG. 8A.

However, such apparatus 1100 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the apparatus 1100 presented herein may be used in any desiredenvironment. Thus FIGS. 15A-15B (and the other FIGS.) may be deemed toinclude any possible permutation.

As shown in FIG. 15A, apparatus 1100 includes a transducer structure1102 having spacer layers 814, 816 sandwiched between shields 806, 804and electrical lead layers 1104, 1106 respectively. At least one of thefirst and second electrical lead layers may be a stitched lead.According to the present embodiment, which is in no way intended tolimit the invention, both electrical lead layers 1104, 1106 are stitchedleads which include a main layer 1108, 1110 and a preferably thickerstitch layer 1114, 1112 thereon, respectively. Vias 1113, 1115 may becoupled to a respective electrical lead layer 1104, 1106. The mainlayers 1108, 1110 may be made during formation of the transducerstructure 1102, while stitch layers 1112, 1114 may be drilled andbackfilled after formation of the transducer structure 1102 usingprocesses and/or in a direction which would be apparent to one skilledin the art upon reading the present description.

As shown, the stitch layers 1112, 1114 may be recessed from a mediafacing side of the main layer 1108, 1110, e.g., the side closest to themedia facing side 850. By stitching a second layer of lead material,e.g. the stitch layer 1112, 1114, which is preferably recessed beyond aback edge 826 of the sensor 808 in the height direction H, theresistance associated with the electrical lead layers 1104, 1106 maydesirably be reduced, e.g., relative to routing either of the leads pasta back edge of the respective shield. As shown in FIG. 15A, the upperand lower shields 806, 804 are insulated from the electrical lead layers1104, 1106 by insulative spacer layers 1120, 1122.

In various embodiments, the main layers 1108, 1110 and/or a stitchlayers 1112, 1114 of either of the stitched electrical lead layers 1104,1106 may be constructed of any suitable conductive material, e.g., whichmay include Ir, Ru, Pt, NiCr, Ta, Cr, etc.; a laminated structure of Ta(e.g. Ta/X/Ta); etc.

Looking to FIG. 8B for reference, in a preferred embodiment of thetransducer 1102, the width of the spacer layers 816, 814 in across-track direction 854 may be greater than the width w₂ of the freelayer 818 of the sensor 808.

FIG. 15B shows a partial side view of an illustrative embodiment of thetransducer 1102 in which the electrical lead layers 1104, 1106 may notbe in electrical communication with the upper and lower shields 806, 804as shown by an insulating spacer layer 1122 between the electrical leadlayer 1106 and the upper shield 806, and the insulating spacer layer1120 between the electrical lead layer 1104 and the lower shield 804.FIG. 15B shows the electrical lead layers 1104, 1106 in the partial sideview in which the stitched leads include a main layer 1108, 1110 and apreferably thicker stitch layer 1114, 1112 thereon, respectively. Theedges of the spacer layers 814, 816 may be proximate to the edges of thesensor 808 but separated therefrom by the respective electrical leadlayer 1104. 1106. An insulating layer 832 may at least partiallysurround the hard bias 830 such that the insulating layer 832 may bepositioned between the hard bias 830 and the sensor 808 as well asbetween the hard bias 830 and the electrical lead main layer 1110.

According to some approaches, the at least one of the upper and lowershields 806, 804 not having a current (e.g., a read sense current)passing therethrough may be coupled to a bias voltage source. In otherwords, at least one of the upper and lower shields 806, 804 may becoupled to a bias voltage source. According to other approaches, one orboth of the shields may be coupled to an electrical connection (e.g., alead), but may not carry any current therethrough.

As mentioned above and looking back to FIGS. 15A-15B, the stitchedelectrical lead layer configuration implemented in transducer structure1102 desirably reduces the resistance associated with the routing eitherof the leads beyond a back edge of the respective shield. For example,in an embodiment where Ru is used as the top lead material, theresistivity “ρ” would be about 7.1 micro-ohms/cm. A single lead withthickness of 30 nm would have a sheet resistivity (p/thickness) equal toabout 2.3 ohms/square. This implies that if the top lead design had 6“squares” of lead geometry, the lead resistance would be about 13.8ohms. However, by implementing a stitched layer above the main layer ofthe stitched electrical lead layer, the total lead resistance would besignificantly reduced. For example, consider a stitched lead of Ru witha thickness of 45 nm covering 5 of the 6 “squares” of the lead geometry.The lead region where the stitched structure and the initial leadoverlay has a net thickness of about 75 nm and a sheet resistivity equalto 0.95 ohms/square. Implementing a stitched electrical lead layer asdescribed above would reduce the lead resistance to 7.3 ohms or by about45%. Embodiments described herein may or may not implement the stitchedelectrical lead layers 1104, 1106, depending on the preferredembodiment.

In still further approaches, one or more of the electrical lead layersmay be an extension of a layer itself, or a separately-depositedmaterial. Establishing an electrical connection to a magnetic laminationproximate to the sensor may create a configuration in which portions ofthe magnetic shields of an apparatus are not biased or current-carrying.In such embodiments, the electrical lead layers included between thesensor structure and the magnetic shield may serve as an electricallead. Moreover, at least one of the upper and lower shields 806, 804 maybe a floating shield, and thereby may not be biased or current-carrying.

Various embodiments described herein are able to provide bi-directionalprotection for CPP transducers against shorting which may otherwiseresult from passing magnetic media over such transducers. Implementing aspacer layer having a high resistivity to smearing and/or plowingbetween the CPP transducer layer and each of the conducting leadportions of the transducer stack without hindering the flow of currentthrough the sensor enables the embodiments herein to maintain desirableperformance over time. Moreover, as previously mentioned, although it ispreferred that an spacer layer is included on either side of a sensoralong the intended direction of tape travel, some of the embodimentsdescribed herein may only include one spacer layer positioned betweenone of the leads or sensor and the shield closest thereto, such that theat least one lead is electrically isolated from the shield closestthereto.

Various embodiments may be fabricated using known manufacturingtechniques. Conventional materials may be used for the various layersunless otherwise specifically foreclosed. Furthermore, as describedabove, deposition thicknesses, configurations, etc. may vary dependingon the embodiment.

It should be noted that although FIGS. 8A-8C, 9-10, 13, 14, and 15 eachillustrate a single transducer structure (transducer structures 802,862, 902, 1002, 1102), various embodiments described herein include atleast eight of the transducer structures above a common substrate, e.g.,as shown in FIG. 2B. Furthermore, the number of transducer structures ina given array may vary depending on the preferred embodiment.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

1. An apparatus, comprising: a transducer structure having: a lowershield; an upper shield above the lower shield, the upper and lowershields providing magnetic shielding; a current-perpendicular-to-planesensor between the upper and lower shields; an electrical lead layerbetween the sensor and one of the shields, wherein the electrical leadlayer is in electrical communication with the sensor; and a spacer layerbetween the electrical lead layer and the one of the shields, wherein aconductivity of the electrical lead layer is higher than a conductivityof the spacer layer, wherein a width of the electrical lead layer in across-track direction is greater than the width of a free layer of thesensor.
 2. An apparatus as recited in claim 1, wherein the electricallead layer is present between the sensor and the upper shield, wherein asecond electrical lead layer is present between the sensor and the lowershield, wherein the spacer layer is present between the upper shield andthe electrical lead layer, wherein a second spacer layer is presentbetween the lower shield and the second electrical lead layer.
 3. Anapparatus as recited in claim 1, wherein the spacer layer includes atleast one of: aluminum oxide, chrome oxide, silicon nitride, boronnitride, silicon carbide, silicon oxide, titanium oxide, and titaniumnitride.
 4. An apparatus as recited in claim 3, wherein the spacer layerincludes silicon nitride.
 5. An apparatus as recited in claim 3, whereinthe spacer layer includes aluminum oxide.
 6. (canceled)
 7. An apparatusas recited in claim 1, wherein the electrical lead layer includes a mainlayer and a stitch layer thereon, the stitch layer being recessed from amedia facing side of the main layer.
 8. An apparatus as recited in claim1, wherein the spacer layer is electrically insulating.
 9. (canceled)10. (canceled)
 11. An apparatus as recited in claim 1, wherein thesensor is a tunneling magnetoresistive sensor.
 12. An apparatus asrecited in claim 1, wherein a width of the spacer layer in a cross-trackdirection is greater than the width of a free layer of the sensor. 13.An apparatus as recited in claim 1, wherein the electrical lead layer ispresent between the lower shield and the sensor, wherein the electricallead layer extends beyond a back edge of the sensor in an element heightdirection.
 14. (canceled)
 15. An apparatus as recited in claim 1,wherein the electrical lead layer is present between the upper shieldand the sensor, wherein the electrical lead layer extends beyond a backedge of the sensor in an element height direction.
 16. An apparatus asrecited in claim 1, wherein the electrical lead layer is present betweenthe upper shield and the sensor, wherein the electrical lead layer doesnot extend to a back edge of the sensor in an element height direction.17. An apparatus as recited in claim 1, comprising: a drive mechanismfor passing a magnetic medium over the sensor; and a controllerelectrically coupled to the sensor.
 18. An apparatus, comprising: atransducer structure having: a lower shield; an upper shield above thelower shield, the upper and lower shields providing magnetic shielding;a current-perpendicular-to-plane sensor between the upper and lowershields; a first electrical lead layer between the sensor and the uppershield; a second electrical lead layer between the sensor and the lowershield; a first spacer layer between the first electrical lead layer andthe upper shield; and a second spacer layer between the secondelectrical lead layer and the lower shield, wherein the first and secondelectrical lead layers are in electrical communication with the sensor,wherein a width of the second electrical lead layer in a cross-trackdirection is greater than a width the sensor.
 19. An apparatus asrecited in claim 18, wherein the second electrical lead layer extendsbeyond a back edge of the sensor in an element height direction.
 20. Anapparatus as recited in claim 18, wherein the width of the firstelectrical lead layer in the cross-track direction is greater than awidth of a free layer of the sensor.
 21. An apparatus as recited inclaim 14, wherein the spacer layer is electrically insulating.